The semiconductor industry's continuing drive toward integrated circuits with ever decreasing geometries, coupled with its pervasive use of highly reflective interconnect materials, such as polysilicon, aluminum, refractory metals, and metal silicides, has led to increased photolithographic patterning problems. Unwanted reflections from these underlying interconnect materials, during the photoresist patterning process, cause the interconnect photoresist pattern and the resulting interconnect to be distorted. This problem is further compounded when photolithographic imaging tools having ultraviolet (UV) and deep ultraviolet (DUV) exposure wavelengths are used to generate the photoresist patterns.
One technique proposed to minimize reflections from an underlying reflective interconnect material is to form an anti-reflective coating over it prior to photoresist patterning. Adhesion between the anti-reflective coating and the underlying interconnect material, however, is often poor and the anti-reflective coating delaminates from the underlying interconnect material, and as a result, integrated circuit yields are degraded. Therefore, the formation of interconnects with an overlying anti-reflective coating is difficult to achieve, and the fabrication of advanced integrated circuits with submicron interconnect geometries is limited.
Accordingly, a need exists for a method that allows interconnects to be formed in an integrated circuit with an anti-reflective coating.